RCW 42.04.020: Eligibility to hold office.

That no person shall be competent to qualify for or hold any elective public office within the state of Washington, or any county, district, precinct, school district, municipal corporation or other district or political subdivision, unless he or she be a citizen of the United States and state of Washington and an elector of such county, district, precinct, school district, municipality or other district or political subdivision.